| 3019766 |
Concar DW, Hill HA, Moore GR, Whitford D, Williams RJ: The modulation of cytochrome c electron self-exchange by site-specific chemical modification and anion binding. FEBS Lett. 1986 Sep 29;206(1):15-9.
The site-specific chemical modification of horse heart cytochrome c at Lys-13 and -72 using 4-chloro-3,5-dinitrobenzoic acid (CDNB) increases the electron self-exchange rate of the protein. In the presence of 0.24 M cacodylate (pH* 7.0) the electron self-exchange rate constants, kex, measured by a 1H NMR saturation transfer method at 300 K, are 600, 6 X 10 (3) and 6 X 10 (4) M-1 X s-1 for native, CDNP-K13 and CDNP-K72 cytochromes c respectively. Repulsive electrostatic interactions, which inhibit cytochrome c electron self-exchange, are differentially affected by modification. Measurements of 1H NMR line broadening observed with partially oxidised samples of native cytochrome c show that ATP and the redox inert multivalent anion Co (CN) 3-6 catalyse electron self-exchange. At saturation a limiting value of approximately 1.4 X 10 (5) M-1 X s-1 is observed for both anions. |
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